Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the ...Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the partition of Cu2+ in the two-phase system containing N-n-dedecane-L-hydroxyproline, was investigated. The formation constant of binary cpmplex(Li2Cu) was obtained by regression. The influence of pH, concentrations of Cu2+ and chiral ligand, and solvents on partition coefficients(K) and separation factor(α), was discussed. The experimental results show that Li forms more stable ternary complex with D-mandelic acid than with L- mandelic acid. There is a large influence of pH on K and α. At low pH values (<3.5), formation of binary complexes is thermodynamically unfavourable. K and α are best when pH values are above 3.5 and the molar ratio of chiral ligand to Cu2+ is 2:1. At the same time, solvents influence K and α very much.展开更多
Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic so...Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic solvents and concentrations of phosphate salt on partition coefficient(K) and separation factor(α) were investigated. The results show that L-tartaric esters studied all form more stable diastereomeric complexes with D-enantiomer than with L-enantiomer. With rise of pH, K decrease, but α increase. With addition of length of alkyl chain of L-tartaric esters, K and α decrease. Organic solvents and concentrations of phosphate salt also show a great influence on K and α. K L, K D and α are 2.523, 2.674 and 1.06, respectively, when mandelic acid enantiomers were extracted by di-O-pentyl-L-tartaric ester in n-decanol at pH=2.3.展开更多
文摘Based on chiral ligand exchange, the distribution behavior of mandelic acid enantiomers in the two-phase system containing copper ion(Ⅱ)(Cu2+) and N-n-dedecane-L-hydroxyproline (L), was studied. At different pH, the partition of Cu2+ in the two-phase system containing N-n-dedecane-L-hydroxyproline, was investigated. The formation constant of binary cpmplex(Li2Cu) was obtained by regression. The influence of pH, concentrations of Cu2+ and chiral ligand, and solvents on partition coefficients(K) and separation factor(α), was discussed. The experimental results show that Li forms more stable ternary complex with D-mandelic acid than with L- mandelic acid. There is a large influence of pH on K and α. At low pH values (<3.5), formation of binary complexes is thermodynamically unfavourable. K and α are best when pH values are above 3.5 and the molar ratio of chiral ligand to Cu2+ is 2:1. At the same time, solvents influence K and α very much.
文摘Distribution behavior of mandelic acid enantiomers was examined in a two-phase aqueous-organic solvent mixture containing L-tartaric esters. The influences of pH, length of alkyl chain of L-tartraic esters, organic solvents and concentrations of phosphate salt on partition coefficient(K) and separation factor(α) were investigated. The results show that L-tartaric esters studied all form more stable diastereomeric complexes with D-enantiomer than with L-enantiomer. With rise of pH, K decrease, but α increase. With addition of length of alkyl chain of L-tartaric esters, K and α decrease. Organic solvents and concentrations of phosphate salt also show a great influence on K and α. K L, K D and α are 2.523, 2.674 and 1.06, respectively, when mandelic acid enantiomers were extracted by di-O-pentyl-L-tartaric ester in n-decanol at pH=2.3.
